Heatsink design with thermal insulator to reduce encoder temperature

Abstract

An electric motor assembly including a housing, an electric motor supported in a motor compartment of the housing, an encoder operatively coupled to the electric motor and supported in an encoder compartment of the housing, and a heat sink surrounding at least a portion of the encoder, the heat sink in thermal contact with an end cap of the housing at least partially defining the encoder compartment, whereby the heat sink is adapted to absorb heat from the encoder and conduct heat to the end cap.

The invention claimed is: 
     
       1. An electric motor assembly comprising:
 a housing; 
 an electric motor supported in a motor compartment of the housing; 
 an encoder operatively coupled to the electric motor and supported in an encoder compartment of the housing; 
 a thermal insulator between the motor compartment and the encoder compartment for thermally isolating the motor compartment from the encoder compartment; 
 a heat sink surrounding at least a portion of the encoder, the heat sink in thermal contact with an end cap of the housing at least partially defining the encoder compartment, whereby the heat sink is adapted to absorb heat from the encoder and conduct heat to the end cap; and 
 a first thermal pad interposed between the encoder and the heat sink; 
 wherein the first thermal pad is a resilient thermal pad interposed in an annular space between the encoder and the heat sink. 
 
     
     
       2. An electric motor assembly as set forth in  claim 1 , wherein the first thermal pad is a silicone fiberglass reinforced thermal pad. 
     
     
       3. An electric motor assembly as set forth in  claim 1 , wherein the first thermal pad secured to at least one of the encoder or heat sink. 
     
     
       4. An electric motor assembly as set forth in  claim 3 , further comprising an adhesive securing the first thermal pad to at least one of the encoder or heat sink. 
     
     
       5. An electric motor assembly as set forth in  claim 1 , wherein the heat sink includes a central cavity adapted to receive the encoder. 
     
     
       6. An electric motor assembly as set forth in  claim 5 , wherein the encoder and the heat sink are generally cylindrical and arranged coaxially. 
     
     
       7. An electric motor assembly as set forth in  claim 1 , further comprising a second thermal pad interposed between the heat sink and the end cap. 
     
     
       8. An electric motor assembly as set forth in  claim 1 , wherein the heat sink includes a plurality of radially extending fins. 
     
     
       9. An electric motor assembly as set forth in  claim 1 , wherein the heat sink is a monolithic cast structure. 
     
     
       10. An electric motor assembly as set forth in  claim 9 , wherein the heat sink is diecast aluminum. 
     
     
       11. An end cap assembly for an electric motor assembly comprising:
 an end cap housing having an encoder compartment; 
 a heat sink mounted to the end cap housing; 
 wherein the heat sink includes a cavity extending between and opening to opposite axial end faces of the heat sink for receiving an encoder of the electric motor assembly, and a first thermal pad fixed to an inner circumferential surface of the cavity, the heat sink being in thermal contact with the end cap housing whereby when the end cap assembly is attached to an electric motor, the heat sink is adapted to absorb heat from the encoder and conduct heat to the end cap housing; 
 wherein the first thermal pad is a resilient thermal pad. 
 
     
     
       12. An end cap assembly as set forth in  claim 11 , wherein the first thermal pad is a silicone fiberglass reinforced thermal pad. 
     
     
       13. An end cap assembly as set forth in  claim 11 , wherein the first thermal pad is secured to at least one of the encoder or heat sink. 
     
     
       14. An end cap assembly as set forth in  claim 13 , further comprising an adhesive securing the first thermal pad to at least one of the encoder or heat sink. 
     
     
       15. An end cap assembly as set forth in  claim 11 , wherein the heat sink is an annular shape. 
     
     
       16. An end cap assembly as set forth in  claim 11 , wherein the cavity is cylindrical and centrally located. 
     
     
       17. An end cap assembly as set forth in  claim 11 , wherein the heat sink is a monolithic cast structure. 
     
     
       18. An end cap assembly as set forth in  claim 14 , wherein the heat sink is diecast aluminum. 
     
     
       19. An electric motor assembly as set forth in  claim 1 , wherein the resilient thermal pad accommodates relative movement between the encoder and the heat sink. 
     
     
       20. An end cap assembly as set forth in  claim 11 , wherein the first thermal pad accommodates relative movement between the heat sink and encoder.